1. Field of the Invention
The present invention relates to an improvement in a bicycle frame and, more particularly, to a bicycle frame which can absorb shocks during running to provide a more comfortable ride and which exhibits improved durability and running performance, thus attaining improved safety of ride.
2. Description of the Prior Art
A bicycle has been designed in such a way that impact is eased by a front fork which is bent in response to any shock to absorb it. Because the provision of a suspension system has been considered to be incompatible with the basic requirements for making a bicycle lighter and more rigid, the suspension system has not been employed so far. Recently, however, the bicycle materials have been made lighter and, in addition, more comfortable ride is greatly demanded. According to the remarkable popularity of mountain bicycles (MTB), moreover, various kinds of bicycle races have become popular, including offroad and downhill rides. Thus, to absorb shock caused by rough roads is greatly demanded.
Recently, researches have been carried out on bicycles in which shocks are absorbed by the front fork or by a frame head portion incorporating a reinforced urethane resin therein, as well as by a suspension provided in the saddle.
Nevertheless, a defect of these various suspensions is that they only absorb shocks to which the front wheel or the saddle portion is subjected, so that the shock absorption has been undesirably limited. The shock absorption capability of bicycles on the rear wheel side is the most important factor in the view points of performance and comfort of ride. There have been no bicycles which possess such a capability and a high rigidity. The conventional bicycles have been greatly improper particularly in respect of the absorption of shocks on both front and rear wheel sides during offroad rides.